This program is designed to analyze the biodynamic membrane features of cells which present antigen to the immune system and to relate this analysis to the antigens immunogenicity. The three cell systems to be studied are: 1) Antigen presenting cells (APC), presenting their own alloantigens to histoincompatible T cells; 2) APC presenting non-constitutive antigens to syngeneic T cells; 3) Tumor cells presenting defined tumor associated antigens and also non-constitutive antigens to syngeneic T cells. We plan to 1) isolate special antigen presenting cells (APC) and define their ability to present TNP and other antigens to the immune system in a specialized manner; focussing on the induction of an immune response which is relatively resistant to suppression. 2) Analyze the membrane residence time (MRT) of defined membrane components on these cells, and compare them with the MRT of the same components on other APC. The components to be measured include: I-A, I-J, I-E, H-2K, H-2D, IgM, IgD, tumor associated antigens and foreign non-constitutive antigens. 3) Determine the subcellular factors which regulate MRT. 4) Determine the physical form of shed membrane components, in particular their association with lipids. 5) Alter the MRT of the components listed and determine the effect of the alteration on the ability of the cells to present antigen. 6) Perform studies similar to those listed above on tumor lines with varying immunogenicity, including studies on the tumor associated antigens which elicit a protective immune response. 7) Determine the factors involved in getting antigens on to specialized APC in a "physiological" fashion.